RU2606142C2 - Device and method for powder material pressing - Google Patents

Abstract

FIELD: ceramic industry.

SUBSTANCE: invention relates to powder material compaction and can be used during ceramic tiles moulding. Powder material layer pressing device comprises transfer surface, located below it pressing surface and flexible pressing surface. Latter is installed with transfer surface overlapping. Device includes pressing facilities, made with possibility to press pressing surface against transfer surface, as well as flexible and resilient pliable facility to hold powder material layer in transverse direction. Layer expansion compensation is provided by facilities, located after pressing facilities in powder material layer movement direction. Said compensation facilities are separated from pressing facilities and comprise lower and upper plates. Upper plate has at least three pistons, each of which is located in direct contact with upper pressing surface and connected with control unit. Latter performs independent control over each piston, acting with differential pressure.

EFFECT: result is provision of compensation pressure constant value applied to layer along entire width of powder material layer.

14 cl, 5 dwg

Description

FIELD OF THE INVENTION

This invention relates to a device for pressing a layer of powder material, mainly in the field of molding ceramic tiles or slabs.

BACKGROUND

Known devices for molding ceramic tiles containing a movable transport surface, on which ceramic powder is gradually supplied so as to form a layer. The transport surface is generally limited by a movable and flexible conveyor belt. The powder layer is supplied by the transport surface through a continuous type pressing system, that is, through a system designed to compress the powder layer as it gradually progresses on the transport surface.

The pressing system, as a rule, contains two flexible pressing surfaces installed with overlapping each other and made with the possibility of movement in the same direction in which the transport surface is moving. In addition, the pressing surfaces are usually formed by a corresponding movable and flexible tape. The lower pressing surface is located below the transport surface and is in contact with it in such a way that it rests on said transport surface, while the upper pressing surface is located at a predetermined height above the transport surface. In a given area, the pressing surfaces move directionally between special pressing means, for example, between a pair of aligned rollers that provide local pressing of the upper pressing surface to the lower pressing surface to compress the layer of powders that are on the transport surface.

In addition, the pressing system usually contains two parallel lateral edges, which are designed to hold the ceramic powder layer on the transport surface during pressing to provide a bulk density of the powder layer more uniform in the width direction. These lateral edges are resiliently flexible to allow compression under the influence of pressing surfaces. After passing through the pressing system, the transport surface finally delivers a layer of pressed powder through a subsequent cutting section, designed to separate the layer of pressed powder into separate plates of a given size.

The pressing pressure that can be applied to the powder layer by a molding device of the type described above is currently limited to relatively low values, up to a maximum of about 200 kg / cm ² , which is usually not enough to produce high-quality finished products. In this regard, plates of pressed powder are usually also subjected to the second stage of pressing, usually by traditional discrete stamping, in order to achieve higher and more acceptable values of pressing pressure, usually in the range of 250-500 kg / cm ² .

There are several reasons for this technological disadvantage of tape molding devices. One of them is that immediately after the pressing means, the layer of compressed powder tends to expand spontaneously. Due to this spontaneous expansion, the degree of which is usually proportional to the pressing pressure, the integrity of the powder layer may be impaired and cracks and / or tears may form, which make the powder layer completely unsuitable or seriously defective. To eliminate this drawback, in the installation for pressing, immediately after the pressing means, usually also provide means to compensate for the expansion of the layer of pressed powder. These compensating means have the function of "accompanying" the expansion, that is, slowing it down, to prevent cracking and / or the formation of gaps in the layer of compressed powder.

Means for compensating the expansion may contain a pair of plates installed overlapping each other, between which the pressing surfaces are guided after passing through the pressing means. These plates perform the function of keeping the upper pressing surface pressed against the lower pressing surface so that the pressed powder layer is pressured to compensate for expansion less than the pressing pressure applied by the pressing means. In particular, the top plate of the pair can be tilted slightly so that the generated compensation pressure gradually decreases as the powder layer moves away from the pressing means while moving it forward. An embodiment of this solution provides for the replacement of the top plate with a flexible plate that is supported by a number of lifts located next to each other in the transverse direction relative to the direction of advancement of the conveyor belt. In particular, each hoist comprises a cylinder made in the body of a fixed support, inside of which a piston is attached, attached to a flexible plate. The cylinders are supplied with pressurized fluid, usually oil, so that the pistons press the flexible plate against the upper pressing surface. In particular, the fluid is supplied to the cylinder through a single manifold so that the same pressure is always applied to each piston. Thus, the flexible plate essentially acts as an isostatic shock absorber, which exerts a constant and uniform pressure on the upper pressing surface below it. A solution of this type is fully described in European patent EP 1585620, to which reference will be made.

Despite the fact that this solution provides good results, it was noted that the expansion compensation effect obtained by applying the flexible plate described above is not always uniform in the direction of the width of the powder layer. In particular, it was observed that the expansion of the powders was compensated more efficiently in the center of the layer than on the sides, as a result of which there was still the possibility of unwanted cracks and / or tears along the mentioned side edges. This phenomenon can occur due to the presence of edges intended to laterally hold the powder layer and having a strain coefficient different from the strain coefficient of the ceramic powder, and thus, due to the different compensation of the force exerted by the flexible plate, so that the compensation pressure actually transmitted to the layer powder is not constant in the width direction.

A solution aimed at eliminating the above-described drawback was proposed in document WO 02/076715, in the field of production of wood chip panels.

This document discloses a press with two tapes for the continuous production of circuit boards, comprising two metal compression tapes rotating in a vertical plane, the tapes being supported by a rigid pressing plate and moving one above the other, at least one of said pressing plates being exposed to at least at least one set of pressing means adjacent to each other in the direction transverse to the movement of the tapes, and forming several parallel rows under the pressing plate in the direction moved I, and the pressing means of each row are not dependent on each other. Said press comprises a device for applying to at least one of said pressing plates a predetermined bending moment in the transverse plane of the plate orthogonal to the direction of movement of the tapes.

The suitability of such an apparatus for compensating for the expansion of a layer of a compressed powder by applying differential pressure to the powder in the transverse direction relative to the direction of advancement has not been confirmed.

SUMMARY OF THE INVENTION

The purpose of this invention is to eliminate or at least effectively mitigate the effects of this drawback of devices known in the art through the use of a simple, rational and inexpensive solution.

This goal is achieved thanks to the characteristics of the invention indicated in the independent claims. The dependent claims provide preferred and / or most effective aspects of the invention.

In particular, a device is proposed for pressing a layer of powder material, comprising a transport surface having the ability to move and configured to maintain and advance the layer of powder material along a predetermined direction of movement, a pressing surface having the ability to move and made flexible and installed with overlapping transport surface, and essentially made with the ability to move in the same direction of advancement, pressing means made with possible Stu pressing of said pressing surface of the transport surface for pressing the layer of powder material placed therebetween, and means for compensating for expansion of the layer of powder material located downstream of the pressing means and intended for pressing the pressing surface of the transport surface with differentiated pressure in the transverse direction relative to the direction of advancement.

Thus, in order to effectively compensate for the expansion of the layer of powder material also along the sides, the regulation of the pressure applied by the compensation means at the edges of the pressing surface may preferably be different from the regulation of the pressure applied in the center. In particular, the pressure applied by the compensation means can preferably be adjusted to ensure that the compensation pressure actually transmitted to the powder material layer is substantially constant along the entire width of the layer.

According to one aspect of the invention, said transport surface and said pressing surface are each limited by a respective movable belt.

According to another aspect of the invention, said means for compensating comprises at least one row of pistons aligned with the pressing surface and located next to each other in the transverse direction relative to the direction of advancement, each of the pistons being placed with the possibility of movement in the corresponding receiving cavity, which is made in the body of the base and communicates with the fluid supply system under pressure to press the piston to the pressing surface located beneath it, and the system supply is designed to control the pressure of the fluid in the receiving cavity of each piston of the series, regardless of the pressure of the fluid in the receiving cavities of the other pistons of the series.

Thanks to this solution, the force exerted by each piston on the pressing surface located beneath it can preferably be adjusted independently of the pressure of the other pistons in the row. For example, these pressures can be adjusted so that a lower force is applied at the center of the pressing surface and a higher pressure at the edges. In particular, the forces exerted by the pistons can be selected so that regardless of the presence of lateral retaining edges, the pressing surface can actually transmit the powder material the same expansion compensation pressure along the entire width of the layer.

In order to make this result particularly effective, in one aspect of the invention, said series of pistons comprises at least three pistons.

According to another aspect of the invention, each piston of the row is essentially made in the form of a plate, which is placed in the corresponding receiving cavity and is configured to move in the direction of its thickness.

This particular configuration of the pistons has the advantage that the pressure exerted by each of the pistons is generally more uniform and substantially isostatic.

According to another aspect of the invention, each of the pistons located at the ends of the row is aligned, at least partially, with a corresponding edge for laterally holding a layer of powder material.

Thus, the aforementioned end pistons can function more efficiently at the edges of the powder material layer.

In yet another aspect of the invention, the expansion compensation means further comprises a flexible plate that is attached to the pistons of the row and thus placed between the pistons and the pressing surface.

The presence of this flexible plate makes the pressure exerted on the pressing surface by the pistons located above it more uniform.

In an aspect of the invention, the pressurized fluid supply system comprises pumps, each of which is configured to pump fluid into the receiving cavity of a respective row piston.

In this aspect of the invention, a very simple solution is provided for independently adjusting the pressure of the fluid in various receiving cavities.

According to another aspect of the invention, the pressure fluid supply system may further comprise pressure control valves, each of which is located in the connecting pipe between the respective pump and the receiving cavity of the corresponding piston.

Thus, the pressure control in each receiving cavity can be performed more accurately and stably.

In another aspect of the invention, the pressure fluid supply system further comprises pressure sensors, each of which communicates with a receiving cavity of a respective row piston.

Thus, the operators and / or the feed system control device have the ability to continuously control the pressure level applied to each piston.

If we consider the device for pressing in a more general sense, in the aspect of the invention, the means for compensating for the expansion may contain many rows of pistons, similar to those described above and located in series along the direction of advancement of the transport surface.

Thus, the means for compensation essentially contains a grid or a matrix of pistons distributed both in the direction of advancement of the transport surface and in the transverse direction, which increases and significantly improves controllability by expanding the layer of powder material.

In addition, the invention provides a method of pressing a layer of powder material, comprising the following steps:

- advancing a layer of powder material along a predetermined direction of advancement by means of a transport surface configured to move,

- pressing said layer of powder material, as it progresses, by means of a flexible pressing surface mounted with the overlapping transport surface and essentially made with the ability to move in the same direction as the feed direction, as well as by means of pressing means, made with the possibility of pressing said pressing surface to the transport surface,

- compensation for the expansion of the layer of powder material as it moves after passing through the pressing means,

moreover, the compensation step involves pressing the pressing surface against the transport surface with differentiated pressure in the transverse direction relative to the direction of advancement.

This embodiment of the invention essentially achieves the same advantages of the device described above, that is, more efficiently compensating for the expansion of the layer of powder material along its edges as well.

According to an aspect of this embodiment, said differential pressure is controlled so that a constant pressure is applied to the powder material layer in the transverse direction relative to the direction of advancement.

Thus, preferably, a layer of compressed powder of uniform quality can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional characteristics and advantages of the present invention will be apparent after studying the following description, given by way of non-limiting illustrative example with reference to the attached drawings.

FIG. 1 is a schematic side view of a device for pressing a layer of powder material.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG. one.

FIG. 3 is a sectional view on a reduced scale along line III-III of FIG. 2.

FIG. 4 is a cross-sectional view of FIG. 3, according to an embodiment of the invention.

FIG. 5 is a diagram of a pressure fluid supply system associated with the device shown in FIG. one.

DETAILED DESCRIPTION OF THE INVENTION

In the aforementioned drawings, there is shown a device 100 for pressing a layer M of powder material, typically ceramic powder, as part of a method for molding ceramic tiles or slabs.

The device 100 comprises a flexible conveyor belt 105, which is a closed loop around the rollers 110 with horizontal axes, including a series of non-drive return rollers and at least one drive roller configured to drive the conveyor belt 105. The conveyor belt 105 may be made of plastic to have a low cost, low degree of contamination and to be easy to maintain. The upper section of the conveyor belt 105, essentially horizontal, forms a transport surface 106 configured to move, maintain a layer M of powder material and advance it in a predetermined advance direction A.

A layer M of powder material is supplied on said transport surface 106 through a continuous type pressing system 115 configured to gradually press the layer M of powder material as it moves. The pressing system 115 comprises two flexible pressing tapes overlapping each other and comprising a lower pressing tape 120 and an upper pressing tape 125. The pressing tapes 120 and 125 can be made of plastic in order to have a low cost, a low degree of contamination and be easy to maintain.

The lower pressing tape 120 is a closed loop around a pair of horizontal axis driven rollers 121, including a non-driven return roller and a drive roller configured to drive the pressing tape 120. The upper section of the pressing tape 120, essentially horizontal, defines the pressing surface 122 made with the possibility of movement, which is located under the transport surface 106 and is in direct contact with it, so that the surface 106 rests on the surface 122. In addition , the pressing surface 122 is driven to move in the same direction as the advance direction A, and at substantially the same speed as the speed of the transport surface 106, to prevent mutual friction.

The upper pressing tape 125, in turn, is a closed loop around a pair of rollers 126 with horizontal axes, including a non-drive return roller and a drive roller configured to drive the pressing tape 125. The lower section of the pressing tape 125 defines a pressing surface 127 made with the possibility of movement and located above the transport surface 106, and the said surfaces are located at some distance from each other, so that between them a gap d I was passing through a layer M of powder material. The pressing surface 127 is driven to move substantially in the same direction as the advance direction A, and at substantially the same speed as the speed of the transport surface 106, to prevent mutual friction with the powder layer M.

The pressing system 115 further comprises a special pressing means configured to locally press the upper pressing surface 127 against the transport surface 106 to compress the layer M of powder material placed between them. In an illustrative example, the pressing means comprises a pair of overlapping pressing rollers, including a lower pressing roller 130 and an upper pressing roller 135, which have horizontal axes of rotation and are orthogonal to the direction of advancement A. The lower pressing roller 130 is located under the lower pressing surface 122 and is in direct contact with it, and it is located at such a height that allows to maintain the flatness of the transport surface 106. In contrast, the upper pressing roller 135 is located above the upper pressing surface 127 and is located in direct contact with it, and it is located at such a height as to locally press the aforementioned upper pressing surface 127 against the transport surface 106 to reduce the thickness p omezhutka therebetween and thereby pressing the powder material M layer. While the lower pressing roller 130 is mounted in a fixed position, the upper pressing roller 135 is movable by means of hoists 136, which allow the altitude position of the said roller to be changed, i.e. the distance relative to the lower pressing roller 130, for example, depending on the thickness of the layer M the pressed powder material and / or the pressing pressure applied thereto.

To achieve a smoother pressing of the powder material layer M, the pressing means may further comprise a pair of roller blocks installed overlapping each other, including the lower roller block 140 and the upper roller block 145, which are placed in front of the pressing rollers 130 and 135 with respect to the advance direction A. Blocks 140 and 145 of the rollers contain rollers that have horizontal and orthogonal to the direction A of the advancement of the axis of rotation. The rollers of the lower block 140 of the rollers are located under the lower pressing surface 122 and are in contact with it, and they are located in a plane parallel to the direction of advancement A, and at such a height that allows to maintain the flatness of the transport surface 106. In contrast, the rollers of the upper block 145 rollers are located above the upper pressing surface 127 and are in contact with it, and they are located in an inclined plane extending from top to bottom with respect to the direction A of advancement, and are located on a height that allows the gradual approach of the upper pressing surface 127 to the transport surface 106 to gradually reduce the thickness of the gap between them and, thus, gradually pressing the layer M of the powder material.

To improve the uniformity of the pressing of the powder material in the direction of the width of the layer M, the pressing system 115 further comprises means for holding the powder material layer M in the transverse direction. In an illustrative example, said holding means comprises a pair of respective belts 150 and 155, which are movable and located above the conveyor belt 105. The belts 150 and 155, which are movable, are flexible and comprise a closed loop around the respective horizontal horizontal rollers 160 axles, including a number of non-drive return rollers and, possibly, a drive roller, which allows the belt to be moved. In particular, the belts 150 and 155 are movable and driven in such a way that the lower section of each of them is essentially horizontal, has the ability to move in the same direction as the direction A of advancement, and essentially at the same speed as the speed of the transport surface 106. As shown in FIG. 2, said lower sections of the movable belts 150 and 155 are supported on the transport surface 106, being in a position between the transport surface 106 and the upper pressing surface 127, thereby limiting two parallel and mutually spaced edges 151 and 156, which are arranged hold in the transverse direction of the layer M of the powder material during pressing. The movable belts 150 and 155 are made of a material that is quite malleable in the thickness direction, for example rubber or any other plastic material, so that the holding edges 151 and 156 formed by them can be elastically compressed between the pressing surfaces 122 and 127.

Immediately after the pressing means, in the pressing system 115, an expansion compensation means is additionally provided, to which the layer M of powder materials is spontaneously exposed after passing through the pressing step. In particular, this compensation means fulfills the function of “accompanying” the expansion of the powder material, that is, limiting and / or slowing down the extent of this expansion to prevent cracking and / or tearing in the layer M after pressing.

As shown in FIG. 2, the expansion compensation means comprises a bottom plate 165, which is located under the lower pressing surface 122 and is in direct contact with it. The lower plate 165 is substantially horizontal and is located at a height that allows the flatness of the transport surface 106 to be maintained. The compensation means further comprises an upper plate 170, which is installed to overlap the lower plate 165 and is located above the upper pressing surface 127. While the lower plate 165 is installed in a fixed position, the upper plate 170 is supported by hydraulic lifts 175, which provide the ability to change the distance from this plate to the transport surface 106, e.g., depending on the thickness of the layer of powder material M.

In addition, as can be seen in the drawings, the upper plate 170 can swing relative to the lifts 175, thus making it possible to install it at an angle to the transport surface 106. The upper plate 170 carries a series of at least three pistons 180 located in the transverse direction relative to directions of advancement of the transport surface 106. Each row piston 180 is made in the form of a thin plate, essentially horizontal, in this case having a rectangular shape in a plan view (see Fig. 3). In an illustrative example, the central piston 180 is wider than the pistons 180, which are located at the ends of the row and are preferably identical to each other. The end pistons 180 have special dimensions and are arranged so that each of them covers a respective holding edge 151 and 156, while the central piston 180 is so sized and arranged so that it covers only the powder layer M. A number of pistons 180, in turn, carries a flexible plate 185, essentially horizontal, which is located above the upper pressing surface 127 and is made with the possibility of direct contact with it. The flexible plate 185 is preferably positioned in such a way and sized so that it covers both the powder material layer M and the side holding edges 151 and 156. The flexible plate 185 may be made of plastic and attached to the lower surfaces of the pistons 180 by conventional fastening means, which are not explained.

In more detail, each row piston 180 is placed in a corresponding cavity 190 of the upper plate 170, in which it is able to move freely in the thickness direction of said plate, that is, in a substantially vertical direction. As shown in FIG. 5, the receiving cavities 190 are in communication with the system 200, configured to supply a fluid therein under pressure, typically oil, so that the pressure of the fluid in the receiving cavities 190 pushes down the pistons 180 associated with the cavities and, accordingly, underneath them, the flexible plate 185. Thus, the flexible plate 185 supports pressing the upper pressing surface 127 against the upper section of the conveyor belt 105, exerting pressure on the layer M of powder material to compensate for expansion. Typically, this compensation pressure will be lower than the pressing pressure exerted by the pressing rollers 130 and 135 so that the powder material still has the possibility of expansion, but without the formation of cracks or tears in the compressed layer M.

In order to allow the powders to expand to obtain maximum uniformity in the direction of the width of the layer M, the supply system 200 includes means for adjusting the pressure of the fluid in each receiving cavity 190 independently of the other cavities. In an illustrative example, said means comprise three independent functional units 205, each of which is capable of suctioning fluid from the reservoir 210 and supplying it under pressure to a respective receiving cavity 190. Each individual functional unit 205 comprises a pump 215 that communicates with the reservoir 210 through a suction pipe 220 and with a corresponding receiving cavity 190 through the discharge pipe 225, and in the line of the discharge pipe 225 is a pressure control valve 230 and Occupancy pressure 235, located in the same discharge pipe 225 after pressure regulation valve 230. In addition, each function block 205 is associated with an electronic control unit 240, which is programmed to control the operation of the pumps 215 and / or pressure control valves 230 so as to provide a predetermined amount of pressure of the fluid in each receiving cavity 190 independently of the other cavities. In particular, the electronic control unit 240 is programmed so that the pistons 180 can be pressed through the flexible plate 185 onto the upper pressing surface 127 with differentiated pressure in the transverse direction relative to the direction A of the advancement. For example, it is possible to control the pistons 180 located at the end of the row so as to exert a force (upper) on the upper pressing surface 127 that is different from the force exerted by the central piston 180, so that regardless of the compensation effect exerted by the lateral holding edges 151 and 156, the powder material located at the edges of the layer M is subjected to the same compensation pressure as the powder material located in the center.

In FIG. 4 shows an embodiment of the invention in which the top plate 170 carries a plurality of rows of pistons 180 that are arranged sequentially along the direction of advancement of the transport surface 106, forming a kind of matrix or grid of pistons 180. Each row of pistons 180 of the matrix / grid is similar to the series of pistons described above, and connected to a similar fluid supply system 200. A corresponding flexible plate 185 may be attached to each row of pistons 180 of the matrix / grid, or one flexible plate 185 of large dimensions may be attached to all pistons 180 of the matrix / grid. Thanks to this solution, each row of pistons 180 of the matrix / mesh can be controlled to provide a different compensation pressure to the powder layer M, for example, gradually decreasing in the advance direction A, in order to allow more smooth and slower expansion of the powders.

It is obvious that the above-described pressing device 100 can be subjected by a specialist to numerous technical changes specific to a particular application of the device, without departing from the scope of legal protection of the invention defined in accordance with the following claims.

POSITION NUMBERS

one hundred pressing device 105 Assembly line 106 transport surface 110 rollers 115 pressing system 120 lower pressing tape 121 rollers 122 lower pressing surface 125 upper pressing tape 126 rollers 127 upper pressing surface 130 lower press roller 135 upper pressing roller 136 lifts 140 lower roller block 145 top roller block 150 tape 151 edge 155 tape 156 edge 160 rollers 165 bottom plate 170 top plate 175 lifts 180 pistons 185 flexible plate 190 receiving cavity 200 feed system 205 function block 210 storage tank 215 pump 220 suction line 225 discharge pipe 230 pressure control valve 235 pressure meter 240 electronic control unit BUT direction of advancement M powder layer

Claims (19)

1. Device (100) for pressing a layer (M) of powder material, containing a transport surface (106), configured to move along a given direction (A) of advancement and designed to maintain and advance in a specified direction (A) of layer (M) of powder material, a pressing surface (122), made with the possibility of movement and located below said transport surface (106) in direct contact with it, a flexible pressing surface (127) installed with overlapping transport surface (106) and made with the possibility of moving in the direction (A) of advancement, pressing means (130, 135), made with the possibility of pressing said pressing surface (127) against the transport surface (106) for pressing a layer (M) of powder material placed between them, a flexible and resiliently flexible means (150) for holding in the transverse direction a layer (M) of powder material and means (170, 180, 185) to compensate for the expansion of the layer (M) of powder material located after the pressing means (130, 135) in direction of advancement a layer (M) of powder material, wherein said compensation means (170, 180, 185) are separated from the pressing means and comprise a lower plate (165) located under the lower pressing surface (122) in direct contact with it, and an upper plate (170 ) installed with the overlap of the lower plate (165) located above the upper pressing surface (127), characterized in that the upper plate contains at least three pistons (180) located in the transverse direction relative to the direction (A) of advancement, each the piston is located in direct contact with the upper pressing surface (127) and connected to the control unit (205), which independently controls each piston and provides each piston with the possibility of acting with differentiated pressure in the transverse direction relative to the direction (A) of advancement. 2. The device according to claim 1, characterized in that the said transport surface (106) and the pressing surface (127) are formed by a corresponding tape (105, 125) made with the possibility of movement. 3. The device according to claim 1, characterized in that the compensation means (170, 180, 185) for expanding the layer (M) of the powder material contain at least one row of pistons (180) overlapping the pressing surface (127) and located next to each other another in the transverse direction relative to the direction (A) of advancement, each of the mentioned pistons being placed with the possibility of movement in the corresponding receiving cavity (190), which is made in the body (170) of the base and is in communication with the system (200) for supplying a fluid under pressure to push piston (180) towards the press surface (127) located beneath it, wherein said fluid supply system (200) is configured to control the pressure of the fluid in the receiving cavity (190) of each piston (180) of the row, regardless of the pressure of the fluid in the receiving cavities ( 190) other pistons (180) of the series. 4. The device (100) according to claim 3, characterized in that said series of pistons (180) comprises at least three pistons (180). 5. The device (100) according to claim 3, characterized in that each piston (180) of the aforementioned series is made in the form of a plate placed in the corresponding receiving cavity (190) with the possibility of movement in the vertical direction. 6. The device (100) according to any one of paragraphs. 1-5, characterized in that each of the pistons (180) located at the ends of the row, is installed with the overlapping of the corresponding edge (151, 156), designed to hold in the transverse direction of the layer (M) of the powder material. 7. The device (100) according to claim 6, characterized in that the compensation means further comprise a flexible plate (185), which is attached to the pistons (180) of the row and is located between the pistons and the pressing surface (127). 8. The device (100) according to claim 3, characterized in that the pressure fluid supply system (200) comprises pumps (215), each of which is capable of pumping fluid into the receiving cavity (190) of the corresponding piston (180) row. 9. The device (100) according to claim 8, characterized in that the pressure fluid supply system (200) further comprises pressure control valves (230), each of which is located in the connecting pipe (225) between the receiving cavity (190) of the corresponding the piston (180) of the row and the corresponding pump (215). 10. The device (100) according to claim 9, characterized in that the supply system (200) further comprises pressure sensors (235), each of which is connected to the receiving cavity (190) of the corresponding piston (180) of the row. 11. The device (100) according to any one of paragraphs. 1-5, 7-10, characterized in that the compensation means comprises rows of pistons (180), which are arranged in series along the direction (A) of advancement of the transport surface (106). 12. The device (100) according to claim 6, characterized in that the compensation means comprises rows of pistons (180) that are arranged sequentially along the direction (A) of advancement of the transport surface (106). 13. A method of pressing a layer (M) of powder material, including: - advancing the layer (M) of the powder material along a predetermined advancing direction (A) by means of a movable transport surface (106), - holding the layer (M) of the powder material in the transverse direction on the transport surface (106) as it moves, while the specified retention is carried out by means for holding, - the stage of pressing the layer (M) of the powder material as it is advanced by means of a flexible pressing surface (127) installed with the overlapping transport surface (106) and configured to move in the same direction as the direction (A) of advancement, and pressing means (130, 135) configured to press said pressing surface (127) against the transport surface (106), - the step of compensating for the expansion of the layer (M) of the powder material, which is carried out after the pressing step as the layer (M) of the powder material moves along a predetermined direction (A) after passing the pressing means (130, 135), characterized in that the step of compensating for the expansion of the layer (M) of the powder material includes pressing the pressing surface (127) and means for holding in the transverse direction the layer (M) of the powder material in the direction of the transport surface (106) with differentiated pressure in the transverse direction relative to the direction ( A) advancement, wherein said pressing is carried out by means of pistons (180), each of which is connected to a control unit (205) that independently controls each piston. 14. The method according to p. 13, characterized in that the said differential pressure is controlled to ensure that the powder layer of the material is applied constant pressure in the transverse direction relative to the direction (A) of advancement.

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